Pensioner keeps books handy (2,3)
I believe the answer is:
on tap
'handy' is the definition.
(I've seen this before)
'pensioner keeps books' is the wordplay.
'pensioner' becomes 'oap'.
'keeps' is an insertion indicator.
'books' becomes 'nt' (New Testament).
'oap' placed around 'nt' is 'ON TAP'.
(Other definitions for on tap that I've seen before include "Immediately available like beer in pub" , "Constantly available like beer from keg" , "Where to find a washer" , "Freely available" , "Where you may see H or C" .)